Pros: Has Magic Bounce as it's Ability so it is able to bounce back Status Moves. Has fantastic Attack, Special Attack and Speed at 150, 115 and 115 respectively. Immune to Psychic types. Resists Dark and Ghost types. Okay Move Pool.
Cons: Has frail Defences. It's HP is 65 and it's Defence and Special Defence is 60. Has three Weaknesses which are to Bug, Fighting and Fairy types.
Pros: Has Solar Power as it's Ability. Fantastic in Sun. Has 140 in Special Attack and 115 in Speed. Above average Defence and Special Defence. Immune to Psychic types. Resists Ghost, Steel, Fire, Grass, Ice and Dark types.
Cons: Has four Weaknesses which are to Rock, Ground, Water and Fighting types. Not very good Move Pool. Receives more damage from Spikes and Stealth Rock.
In my opinion I'd go with Mega Houndoom over Mega Absol. But that's not to say Mega Absol isn't good and shouldn't be used at all because Mega Absol is still a fantastic Pokémon :)
Hope I helped :)